The present invention relates to an armrest-adjusting mechanism.
An office chair is inevitable for a worker who works in an office. Because such worker always sits on the office chair through a long time during working, a comfortable office chair is required so as to avoid any ill affection on the worker caused by improper sitting attitude. Therefore, the current office chair is mostly designed according to the profile of human body. However, the profile of human body varies and therefore the office chair is often provided with several kinds of adjusting mechanisms, including armrest-adjusting mechanism for meeting the requirements of different persons.
A conventional armrest-adjusting mechanism, as shown in FIG. 1, is mainly composed of a lower support 1, an upper support 2, a rotary disk 3 and a bearing board 4. An upper portion of the lower support 1 is formed with a recess 11. A member having multiple equally spaced and vertically arranged semicircular notches 12 is disposed in the recess 11. Each of the semicircular notches 12 is open in the same direction as the recess 11. In addition, an upright stopper plate 13 is disposed on an outer side of semicircular notches 12. The stopper plate 13 has a length substantially equal to the width of the recess 11. A resilient pressing strip 14 is disposed in the recess 11 on a lateral side of the stopper plate 13 so as to tightly press against the stopper plate 13.
The upper support 2 is a hollow member, having an interior space 21 for receiving the lower support 1. An elliptic hole 22 is formed on the upper support 2 such that when the upper support 2 is fitted onto the lower support 1 at a lowest position, a bottom side of the elliptic hole 22 is flush with a bottom side of the recess 11. Furthermore, on two lateral sides of the elliptic hole 22 are respectively formed two circular depressions 23 for respectively receiving the rotary disk 3 and the bearing board 4.
The rotary disk 3 is an integrally formed member, having an outer swiveling button portion 31 and an inner disk portion 32 received in the elliptic hole 22. The disk portion 32 has a diameter substantially equal to the distance between an upper end and a lower end of the elliptic hole 22 while smaller than the distance between a left end and a right end of the elliptic hole 22. The disk portion 32 has two cylindric projections 321 positioned between the semicircular notches 12 and the stopper plate 13.
The bearing board 4 is disposed in one of the circular depressions 23 and formed with thread holes 41 through which screws 42 pass to secure the rotary disk 3 and bearing board 4 in the upper support 2.
According to the above arrangements, after the upper support 2 is fitted into the lower support 1, the two cylindric projections 321 of the rotary disk 3 are inserted into the semicircular notches 12 of the lower support 1 and pressed by the resilient pressing strip 14 and the stopper plate 13. Therefore, when the rotary disk 3 is rotated, the two cylindrical projections 321 thereof change their positions in the semicircular notches 12 so as to adjust the position of the armrest.
In the above conventional armrest-adjusting mechanism, several shortcomings exist as follows:
1. The cylindrical projections of the rotary disk are inserted into the semicircular notches of the lower support and pressed by the resilient pressing strip and stopper plate, so that when the positions of the cylindrical projections in the semicircular notches change for adjusting the height of the armrest, a considerably large force is required for the cylindrical projections to bias the resilient pressing strip and stopper plate outward. Therefore, it is labor-consuming to adjust the height of the armrest.
2. The adjustment is accomplished by means of interchanging the positions of the two cylindrical projections of the rotary disk in the multiple equally spaced semicircular notches, so that each time the rotary disk is rotated, the armrest only moves through a distance between two adjacent semicircular notches. Therefore, in case it is necessary to adjust the armrest through a long distance, the adjusting procedure will be inconvenient and cost much time.
3. The adjusting mechanism includes many complex components so that the manufacturing cost is high and it is difficult to assemble these components.